Hardware known as a “ferrule loop insert” is often used to make structural connection to concrete structures such as concrete walls, ceilings and floors. Referring to FIG. 1, the typical ferrule loop insert has a loop portion 5 attached to an internally threaded ferrule 7, the ferrule having an open end 8 for receiving an externally threaded member such as a bolt. By various means, the open end 8 is fitted with a plug 9 and positioned above a plywood form 4, and concrete 6 is poured over the form and the ferrule loop insert and allowed to cure. When the form is removed, the ferrule loop insert is left remaining, cast into the concrete. Removing the plug 9 from the end 8 allows for accessing the threads of the ferrule loop insert 7 for making the desired structural connection thereto. FIGS. 2 and 3 show alternative plugs 9a and 9b. 